Instrument for drawing ellipses



sept. 2s, 1954 W. E. MaCGUIRE INSTRUMENT FOR DRAWING ELLIPSES Filed June6, 1952 IIIIII 2 Sheets-Sheet l Arfy Sept' 28, 1954 w. E. MacGUlRl-z2,690,013

INSTRUMENT FOR DRAWING ELLIPSES Filed June 6, 1952 2 Sheets-Sheet 2Patented Sept. 28,V 1954 `INSTRUMENT FOR DRAWING ELLIPSES William E.MacGuire, Louisville, Ky.; Carolyn E. MacGuire, la'dministratrix of saidWilliam E.

MacGuire, deceased Application June 6, 1952, Serial No. 292,161

2 Claims.

lTJhis invention relates generally lto the class of geometricalinstruments and is directed particularly to an improved instrument fordrawing or laying y'out ellipses.

A principal object of the present invention is to provide `an instrumentin 'the nature of a compass by means fof which an ellipse may be drawneasily andrquickly in one complete rotative movement of a markingimplement around a fixed center.

Another object of the invention is to provide an instrument of thecharacter stated wherein means is provided for making an easy and quickadjustment of 'the instrument for the laying out of -ellipses :havingmajor .and minor axes of dilierent .lengths as required.

Still another object of the invention is `to provide an instrument ofthe .character stated employing a fixed .standard fand a markingimplement carrying'arm which is pivoted to the standard for turningmovement thereabout and for swfm'ging movement inward-ly and outwardlyrelativethereto, wherein the dimensions of the desired ellipse :arecontrolled by a single cam element carried [by the Astandard whichfunctions as a guide to vmove the arm inwardly and outwardly relativetothe standard `as the arm .is turned around the standard.

-Still another objectvof the .invention is .to provide, .in anAimplement of the 4above `described character, a `novel .means wherebythe vmarking implement is lmaintained at all ytimes .in contact withvthe Amarking surface as the arm swing-s inwardly and outwardly relativeto the standard during its turning movement around the standard.

A.stillfurther object ofthe invention isto provide in an instrument ofthe character above set forth,.a.means whereby the major and minor axesof the ellipse desired .to be laid 01T, can "be altered by movement .of.the cam .member .longitudinally of .the .standard -and .by oscillationof the cam member on an 4axis extending transversely of the standard.

'Other objects and advantages of lthe invention will become apparent asthe description Vof the same proceeds and the invention will .be .bestunderstood from a consideration of the .following detailed descriptiontaken in connection .with the accompanying drawings forming a part ofthe specification, with the understanding, however, that the inventionis not to ybe limited to the exact details of construction shownand-described since obvious vmodiiicati'ons willzoccur to 'apersonsk-ille'd in the art.

In the drawings:

Figure 1 is a view in elevation of an instrument constructed inaccordance with 'the preferred embodiment of the present invention.

Figure '2 is a longitudinal section taken substantially on the line 2-2of Figure 1.

Figure 3 is an exploded View of the xed standard and parts carriedthereby exclusive of the marker carrying arm.

Figure 4 is a Ysectional View of the cam disk turning annulus carried bythe arm.

Figure 5 is a detail view illustrating the connection between the lowerend of the varm and the clevis ofthe marking element.

Figure 6 is a View in elevation of a ruling pen to 'be used in themarking element.

Figure 7 is a view in side elevation of the instrument showing theattachment of the extension bar and the additional supporting leg.

Figure 8 is a view in plan of the bifurcated leg.

Figure 9 is a transverse section taken -on the line 9-9 of Figure '7.

.Referring more specically to the drawings it will be seen uponreference to Figure l that the' instrument of the present invention isgenerally in the nature of a compass in that it comprises a standard l0which has one end placed upon the surface on which the ellipse is drawn,and an-arxn l2 which is pivotally coupled at one end to the standard andcarries a marking implement upon its other end as hereinafter morespecifically described.

The Vstandard Ill carries upon its lower or bottomend an `element formaintaining the standard in fixed position on the marking surface, suchelement being here shown as in the nature of a circular foot member Ilhaving an upstanding collar I6 in which 'the lower end of the standardI0 is fixed. The base of the foot member I4 carries a number ofdownwardly directed, equidistantlyspaced surface engaging pins I8 whichhold the foot against slipping.

The upper end of the standard Il) has a portion I'a of reduced diameterwhereby there is provided a surrounding shoulder 20. The reduced portionma extends entirely to the upper end of the standard and is providedwith a transverse aperture 22 for the purpose about to be described.

The upper end of the standard carries a rotary head which is generallydesignated 24.

The head 2B comprises a lower plate 26 which is formed integral with theelongate hub 2B through which and the plate, is formed a passage 30 of adiameter to snugly receive the reduced portion Ita of the standard. Thehub, as shown, rests upon the shoulder 223 and is thereby maintainedagainst downward movement on the standard.

Lying upon the top of the plate 2S is a spring plate 3l which has acentral aperture 32 for the portion lea of the standard and resting uponthe spring plate is a control or turning disk 33 which also has acentral aperture Sti to receive the portion lila of the standard.

The three disks or blades ZE, 3l and 33 lie in superimposed relation andare coupled together by screws 3:'3 which pass through aligned aperturesSt, 3l and 38 of the members, the screws being threaded into theapertures 38 in the disk thereby binding the three members together.

Formed integral with the spring plate 3l is a curved leaf spring 385which extends outwardly, downwardly and inwardly from the edge of theplate 3l and terminates in the finger 4t which is of a reduced width.The purpose of this spring is hereinafter set forth.

The top of the disk 3| is laid off in degrees of the circle, for thepurpose hereinafter pointed out, and resting upon the top of the disk 33is a cover disk il which is of slightly smaller diameter than the disk33 and has a recess 42 in the edge thereof, through which one of thedegree indicating members on the top surface of the underlying disk 33may be read. The cover disk di is also centrally apertured with a guidecollar i3 dening the aperture and the upper end of the standard passesthrough this collar and has fixed thereto, just above the collar, by thetransverse pin 4t, the knurled cap d5.

As the cap 45 is fixed to the upper end of the standard and the head 24rests on the shoulder 20 just below the cap it will be seen that thehead is free to turn or rotate about the standard but is prevented fromhaving any material movement lengthwise thereof.

The numeral 46 generally designates the axis determining unit. This unitcomprises a relatively long sleeve di through which the standard, belowthe shoulder 2li passes and which is designed to have movements up anddown on the standard.

The sleeve l has a head dla upon its upper end and at its lower end itcarries the lock screw 48 which has the reduced finger 48d on its innerend which engages in a keyway or key slot 4Q formed in the standard itfrom the foot to the shoulder thereof.

The sleeve head cla has the oppositely positioned radially directedpivot pin holes 5i) therein which extend to the interior of the sleevefor the purpose hereinafter set forth and between the sleeve head lo andthe lock screw et, the sleeve is externally screw threaded as indicatedat 5I.

Threaded on the sleeve Il? is the cam disk positioning nut 52 which isdefined at its top by the outstanding encircling shoulder 53.

Also threaded upon the sleeve il below the disk positioning nut 52, is alock nut 54 which holds the nut 52 in set position,

The numeral 55 designates the axis control cam which is in the form of adisk as shown, having an elongate, relatively wide slot 56 formeddiametrically therein. This slot is of a width to receive the sleevehead 4? and extending into the slot from opposite sides, centrally ofthe ends of the slot, are the pivot pins 56 which enter the holes 5c andengage, at their inner ends, against the standard l0. These 4 pivotpins, which are positioned diametrically of the disk 55 at right anglesto the slot 56, are urged inwardly by springs 5t which are held by thescrews SB.

It will be seen from the foregoing that the axis control cam may berocked on its pivots 5S and the extent of such rocking movement isgoverned by the position of the positioning nut 52, the rim 53 of whichis engaged by the disk 55 when the latter is oscillated to apredetermined extent.

The .arm l2 has the curved shoulder tl at its upper end which joins thetwo spaced ears 62. These ears receive between them the hub 2B and theyhave extended through them and into the hub, the screw pivot pins 63which are aligned transversely of the standard l!! so that the arm l2may swing on an axis perpendicular to the standard and passing throughthe longitudinal center of the latter.

The outer side of the shoulder, which is the side facing away from theears $52, has the wall 64 between the ears G2 on which bears the reducedend it of the leaf spring 39. This spring 3S is tensioned to move itsfree end inwardly toward the standard and accordingly it constantlyexerts inwardly pressure against the upper end of the arm tending toswing the arm toward the standard.

The lower end of the arm I2 is reduced or attened to provide the hingeblade 65 for the purpose hereinafter set forth and between the blade E5and shoulder Si the outer side of the arm i2 is provided with the flatsurface et.

lThe numeral 61 generally designates the cam disk trip which comprises acollar 63 which encircles the arm l2 and which has the opening t9thereof flattened on one side as indicated at 69a, such flattened sideengaging the flat surface 66 of the arm thereby holding the collar.against turning on the arm.

The collar t8 carries a locking screw It which extends through the flatsurface 69a for contact with the flat surface 68 of the arm whereby thecollar is xed in adjusted position on the arm.

The underface of the collar G8 carries on the side of the arm receivingopening 69 opposite from the locking screw 18], a downwardly directedspring pressed pin ll, the control spring for which is designated 12 andthe spring and pin are encased in a suitable sleeve 13 carried on theunderside of the collar. This pin 1l is designed for contact with thetop surface of the axis control disk 55 as will be hereinafter setforth.

The numeral i4 generally designates the marking implement or markingunit which is carried on the free end of the arm l2. rFhis unitcomprises an elongate sleeve or cylinder 'l5 through the upper end ofwhich is threaded a spring compressing screw 16 which engages at itsend, the top end of a coil spring 'il which is housed in the cylinder'ill as shown.

Extending into the cylinder through the open lower end thereof is theshank 18 of a marker or scriber le which may be in the form of a pencilas indicated in Figure l and 2 or in the form of a ruling pen asillustrated in Figure 6 and designated 19a.

The shank f8 of the marking or scribing element has the longitudinal keyslot 8G formed therein, in which is engaged the inner end of theretaining screw tl which is threaded through the side wall of thecylinder M at the lower end thereof. `Since the key slot 8c does notextend al1-ofthe way to `tneupper A`end of the'shank v'18 it Awill Lbeseen kthat the spring *H 4can'move `the shank Vof the marking elementVoutwardly without danger of `having the element Aescape from the 1cylinder. f

Formed integral `with the lewer end of the cylinder 'I4 is a couplingclevis comprising "two spaced ear members' v'82 between which lthetongue 65 of the arm -I2 `is yadapted lto position to Vreceive thevthreaded `,pivot pin 8-3. The ears 82 -of the lclevis are directedIo-bliquely upwardly from vthe lower end yof the cylinder '-14 `so thatwhen the marking implement is coupled with the lower end of the arm I2`such implement will 'have the scriber disposed substantially verticallyfor `contact with the marking surface.

It is believed to beapparent fromtheforegoing that the spring 39 Iwillnormally -hold the marker arm lf2 against the edge or periphery 'of theycam disk 55 so that as the -head 24 is rotated the'arm i2 will movearound the -disk and if kthe disk 55 is set in a -plane which is at vanangle -to the standard I0 other than -a Yright angle the arm vt2 willswing outwardly and inwardly during this rotary movement.

As the arm swings outwardly at Lits lower end from the standard I0 suchvflower end will, of course,.rise from the surfacebut-due to the actionof the -spring 11, as the arm and ,cylinder yrise .the marking .elementwill be moved outwardly or downwardly so that the marking point will bekept in contact with the marking surface.

In the .use of the instrument, the standard lil is,of course, set uponthe marking` surface tobe at the point -of intersection of the long and:short axes of the ellipse whichis tc be .laid out.

The length of the long axis of the ellipse is determined by the heightvvof the disk 55 on the standard I0 as it will beseen 'that the longaxis of .the ellipse willbe parallel Ato :the turning :axis ofthe disk55.

After the proper elevation of the disk on the standard is determined,the disk positioning nut 52 is elevated to swing the disk 55 to ahorizontal position or a position in a plane perpendicular to thestandard l5. The collar 68 is located, before this adjustment, above thedisk 55 and after the disk has been turned to the horizontal positionthe collar 61 is lowered until the plunger 1I contacts the top surfaceof the disk whereupon the collar is xed.

The disk positioning nut is then lowered from the disk and the diskswung into an oblique plane with respect to the standard until it is inproper position where, with the arm I2 against the low edge of the disk,the marker le will designate a point on the marking surface a distancefrom the standard equal to half the length of the short axis of theellipse. The lock nut 54 is then set to prevent the disk from swingingbeyond its selected inclined position.

The ellipse may now be drawn by grasping the disk l33 and rotating thehead 24 so as to swing the marker unit around the standard. If thestarting position of the arm l2 is with the arm in contact with thelowermost part of the periphery of the disk 55, the arm as it ridesalong the rising edge of the disk will swing outwardly from the standardso as to mark off a line leading to one end of the long axis of theellipse and when the arm reaches a position where the trip plunger orpin 1| rides across the axis of the pivot pins 58, the trip pin willeiect the oscillation of the disk 55 to a reverse angle whereupon thearm will continue riding along the edge of the disk down 6 the-fslop'ing side "toward ftheend Aof the short axis of 1the e1lipse- 'Thestated faction up to this vpoint will then lbe :duplicated as the .armmoves around to litslstarting position to `complete `.the :outlining ofith'e ellipse, by the rmarking unit, .on A.the marking surface.

As previously stated, vas the .arm swings outwardly away .from thestandard and naturally tends Lto rise vat its .outer end together withthe cylinder IFM, the marking .element will be maintained 1in contactwith the :marking .surface fby the .faction of the spring Tl .sliding:the marking element .downwardly Vand youtwardly from the cylinder, andfof course, as 'the -s'hort axis'zsi'de fof the :ellipse iis approached.the arm rl2 will 'swing inwardly `.and upward pressure will :be applied.tD the marking element. soas to compress the spring lil.

Where it may be necessary 'to 'reach out from thestandard tl) .to agreater distance .than ywould be convenient to the useof the marking4unit applied directly 'to the lower .end of the arm 1.2, luse may bemade of .the extensionarm 12a as.illus trated '1in Figure?. Thisextension arm I'2arcomprises va `bar of `suitable length, `designated1.21), having at one vend the Vang-ularly extendingtongue.IT20and-atthe'oppositeiend.the oppositely directed angularly vextending`clevis .comprising "the two spaced parallel tongues 12d. The tongue andclevlis fare :disposed to vform .an obtuse .angle `with the `bar andare.in .oppositely ldirected .but "parallel relationasshown. Thus when theterminal blade of the arm i2 is located :between the apertured ears l2dand secured .thereto bythe screw the tongue 1.20 can .be disposed vat`the proper downwardly extending .angle `for proper connect-ion'withthe.side extension 82 of the cylinder l'lof the marking implement.

norder to give further stability to the instrument, particularlywhenusemay be .made vof the extension arm `i2a,1an auxiliary .brace .leg isprovided :such as that shown in Figure 7 :and 'generally designated 85.This auxiliary leg comprises the fork 8'6 having at its top a stem 81,and an angled sleeve 88, in one end of which the stern 8l is positionedand secured by a screw 89 while at the other end of the sleeve is aspring clasp or clip Si) which extends laterally from the sleeve atright angles thereto and which is adapted to frictionally engage aroundthe standard Ill as illustrated.

From the foregoing it will be readily apparent that there is provided bythe present invention an instrument of novel construction by means ofwhich accurate ellipses may be formed easily and quickly by onecontinuous turning movement of the marking implement around the centralpositioning standard. It will also be apparent that by the novelemployment of the obliquely disposed disk and manner in which it ismounted so that it can be raised or lowered as desired according to thelength of the long axis required or disposed at a desired angle inaccordance with the length of the short axis desired, changes can bemade easily and quickly for the easy and accurate formation of ellipsesof different dimensions.

I claim:

1. An instrument for drawing ellipses, comprising a vertical standard, afoot on the lower end of said standard to support the same on a surfaceon which an ellipse is to be drawn, a head unit mounted for turningmovements on the top end of said standard, an arm pivotally coupled atone end to the head unit to swing relative to the standard on an axisperpendicular to the standard, said arm being turnable with said headunit about the standard, a vertically disposed marking implement, a linkhaving reversely curved end portions pivotally connected to andextending between said arm and said implement, a circular disk having acentral opening engaged on said standard, adjustable pivot meanssupporting said disk on said standard, the perimeter of said disk beingtraversed by the arm as it is turned with the head unit relatively tothe standard for guiding the implement in the desired path, and springmeans cooperative with said implement for maintaining the same incontact with said surface, the upper end of said standard being reducedin diameter to provide an annular shoulder upon which the head unit isseated, said head unit being comprised in a lower disk having a hubengaged over said shoulder, the upper end of said arm having an angledportion which is bifurcated to straddle said hub, pivot pins threadedinto said hub through apertures formed in the side portions of thebifurcation, a second disk supported n the first disk, an arcuate leafspring depending from the periphery of said second disk and having anend bearing against the outer side of said arm, a third disk supportedon said second disk and having its top face calibrated in degrees,fastening elements securing said disks together, a cover disk supportedon said third disk and having a aperture through which the degreecalibrations on the latter may be viewed, and a cap element secured onthe top end of said standard to prevent endwise movement of the ydiskassembly on the standard.

2. An instrument for drawing ellpses, comprising a vertical standard, afoot on the lower end of said standard to support the Same on a surfaceon which an ellipse is to be drawn, a head unit mounted for turningmovements on the top end of said standard, an arm pivotally coupled atone end to the head unit to swing relative to the standard on an axisperpendicular to the standard, said arm being turnable with said headunit about the standard, a vertically disposed marking implement, a linkhaving reversely curved end portion pivotally connected to and extendingbetween said arm and said implement, a circular disk having a centralopening engaged on said standard, adjustable pivot means supporting saiddisk on said standard, the perimeter of said disk being traversed by thearm as it is turned with the head unit relatively to the standard forguiding the implement in the desired path, and spring means cooperativewith said implement for maintaining the same in contact with saidsurface, the said adjustable pivot means comprising an exteriorlythreaded sleeve slidable on an intermediate portion of said standard, aset screw carried by said sleeve for its securement in desired positionon said standard, the said guide disk being pivotally mounted in theupper end of said sleeve, a nut threaded on said sleeve, an annularshoulder at the upper end of said nut to support said guide disk inrequired angular relation with respect to said standard and said arm.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 383,696 Bormann May 29, 1888 1,053,686 Weikel Feb. 18, 19131,055,303 Elliott Mar. 4, 1913 1,085,415 Halvorsen et al. Jan. 27, 19141,168,546 Odin Jan, 18, 1916 1,290,812 Wayditch Jan. 7, 1919 2,496,614Arnason Feb. 7, 1950 2,498,798 Edwards Feb. 28, 1950 2,557,500 FairbanksJune 19, 1951 FOREIGN PATENTS Number Country Date 642,517 France May 5,1928 467,805 Germany Nov. 1, 1928

